Preschool behavior of a population-based sample of 144 5-year-old children with birthweights less than 2000g (LBW) was compared with a random sample of 163 normal-birthweight term controls. The Personality Inventory for Children and the Yale Children's Inventory were completed by the mothers, and child behavior during psychometric testing was assessed. Nineteen per cent of the LBW children compared to 4% of controls had behavioral problems as defined by abnormal scores on more than three behavioral measures. The LBW children were more often socially insecure, anxious and difficult to manage, but inattention and hyperactivity were not prominent. The LBW children were not more sensitive to the negative impact of parental risk factors than normal-birthweight children.